One thing I find somewhat difficult is getting the various fonts and sizes and weights to look "just right". What are some good guidelines to follow for font sizes, weights and styles when making web applications?
One problem I have is simply getting stuff to fit on the screen too, like for tables that need quite a few columns and things like this. I find that there are a lot of typographic decisions though... the header, main menu text, side menus, forms, lots of multi-level page content, tables, footers, etc.
What would be the best examples of application-oriented websites that have done a great job that I can maybe borrow ideas from? :P